This application makes reference to and claims all benefits accruing under 35 U.S.C. Section 119 from an application entitled, xe2x80x9cMethod for Fabricating High-Purity Silica Glass Using Sol-Gel Processingxe2x80x9d, filed in the Korean Industrial Property Office on Dec. 16, 1999 and there duly assigned Serial No. 99-58144.
1. Field of the Invention
The present invention relates generally to a method for fabricating silica glass, and in particular, to a method for fabricating high-purity silica glass using a sol-gel process.
2. Description of the Related Art
Silica glass, which is a raw material of high-purity glass articles, has been useful for optical devices, such as optical fiber and photomask for semiconductor. Silica glass is generally manufactured using a natural quartz process, synthetic quartz process, or sol-gel process. Basically, the sol-gel process involves the technique of securing high-purity silica glass using a high purity material as the starting material. When the sol-gel process is used as a liquid phase process, high productivity can be achieved and the composition of the product can be controlled easily compared to other processes. Also, the sol-gel process is economical because almost all steps except sintering are carried out at a low temperature.
A known fabrication method of silica glass using the sol-gel processing is disclosed in detail in U.S. Pat. No. 5,240,488, entitled xe2x80x9cManufacture of vitreous silica product via a sol-gel process using a polymer additivexe2x80x9d.
In the fabrication of silica glass using the sol-gel processing, there are various factors including temperature, composition, pressure, acidity and solvency which have an adverse effect in the transition of sol to gel as well as in the strength of the gel. To overcome this problem, many attempts have been made to secure the flexibility and strength of the gel while preventing cracks that may occur in the drying process. Unfortunately, it is a continuing problem to prevent many cracks when drying the molded gel and during sintering.
It is, therefore, an object of the present invention to provide a method for fabricating high purity silica glass using a sol-gel process, in which cracking during the drying process is minimized.
Accordingly, to achieve the above objective, there is provided a method for fabricating high-purity silica glass using a sol-gel process comprising the steps of: (a) mixing deionized water with a monomer and a dimer to prepare an aqueous premix solution; (b) mixing the aqueous premix solution with a fused silica and a dispersion agent; (c) mixing the resulting mixture to form a dispersed sol; (d) aging the dispersed sol at an ambient temperature to stabilize silica particles, and removing air voids from the sol; and (e) adding a polymerization initiator and a gelation agent to the aged sol.